Description:
<jats:p> Unmanned underwater vehicles (UUVs) have been developed for various applications in ocean engineering. When failures occur to UUVs and result in abnormal operations, the only solution is to abort from the mission due to lack of fault tolerance. The purpose of this study is to investigate a method by which UUVs can continue to operate acceptably following failure occurrences. Based on a unique hierarchical fault detection and identification, this paper presents a control reconfiguration scheme with multiple sliding-mode controllers for each of the hypothesized failure modes from a discrete set [θ<jats:sub>1</jats:sub>, θ<jats:sub>2</jats:sub>,..., θ<jats:sub> n</jats:sub>], which depict the failure status of actuators and sensors. The reconfigured control is a probability weighted average of all the elemental control signals. We apply this method to the steering subsystem of the Naval Postgraduate School (NPS) UUV with simulated rudder and/or sensor failures. The results show that both the heading angle and the steering track have been properly compensated. </jats:p>